Plans for hal 0.5.x

David Zeuthen david at
Tue Dec 14 09:43:03 PST 2004

On Tue, 2004-12-14 at 17:35 +0300, Andrei Yurkevich wrote:
> > My gut feeling is that most USB-based pda's just have a USB serial
> > adapter stuck onto them and in that case it would suffice with just
> > tagging that USB device as 'pda' through device information files. I
> > could be wrong though. 
> Right, at least all PDAs I've seen (and that's been a lot of them) that 
> connect via USB are built this way. They provide some USB device of 
> their own that has got a USB-serial converter bound to that USB 
> interface. However, in the discussion you've mentioned, the idea was to 
> tag that USB device as a PDA. That's ok in case of USB, 

That's exactly the problem hal should solve.

> but when you 
> connect a PDA via serial/IrDA or Bluetooth, you won't have that USB 
> interface device. Instead, you will get a ttyS(n) in case of serial 
> connection, rfcomm(n) for bluetooth and irtty(n) or ircomm(n) for IrDA, 
> all of those being serial interfaces. Moreover, there is a way to 
> distinguish the device connected via these serial interfaces as a PDA or 
> something else, that could be done by HAL itself or a callout. Thus, we 
> could simply tag these serial interfaces with some property like 
> "pda.palm.serial_interface" or "pda.pocket_pc.serial_interface" just to 
> let the interested applications know that these serial ports lead to a 
> PDA device. Finally, some callout/daemon/whatever responsible for 
> establishing a connection with a PDA could do what it needs to when it 
> sees that there is a PDA available behind some serial interface.

For Bluetooth/IRDA/legacy serial port: But in order to bring up those
serial devices some PDA software is already in play - that software
should know itself what the interface is and use it; it doesn't need to
get it from hal. Do you disagree?

However, hal should indeed say "here's a irda serial port", "here's a
legacy serial port", "here's a Bluetooth HCI interface" so said PDA
software knows how to probe for devices there.


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